Based on the early photos, MG Siegler calls it a cross between Path, Instagram, Color, and With. Siegler also suggests that the standalone app will likely be integrated with the iPhone's main Facebook app. But no word yet whether the photo-sharing app will also see a release on Android, BlackBerry, or Windows Phone.

Given how many photos are uploaded to Facebook each month -- roughly six billion -- it'd be foolish not to.

As for third party apps, GigaOm's Darrell Etherington believes there will be enough room for competitors to coexist in the photo-sharing arena.

"[Stickier] apps like Instagram should be able to stay afloat, even with Facebook throwing up a huge wake. The iPhone-only app recently hit the 5 million user milestone, with roughly 26 million photos taken each month," Etherington writes. "It's a far cry from Facebook's volume, but consider that Instagram is just eight months old, with only a single mobile client on a single platform."

He adds, "Like Twitter, Instagram offers a different set of experiences and expectations, maybe precisely because you’re extending beyond your normal social graph."